There is a technique in which a plurality of DC-DC converters are mounted on a motherboard, and electric power supplied from a direct current (DC) power supply is distributed to the DC-DC converters and then supplied to a processor.
Furthermore, there is a technique in which a power supply device of an overvoltage protection circuit includes a main DC-DC converter and a sub-DC-DC converter.
When a DC-DC converter is disposed near an electronic component such as a processor (hereinafter, properly referred to as an “electronic component”) to supply an electric current to the electronic component, a mounting space available for other components is narrowed in the vicinity of the electronic component. In particular, when a large DC-DC converter is disposed near the electronic component to supply a large current, a mounting space available for other components is further narrowed.
Whereas, a structure is also considered in which a DC-DC converter is mounted on a substrate that is separate from a load component mounting substrate and an electric current is supplied through a metal pillar, so that a mounting space available for other components is secured around the electronic component.
However, when a large amount of direct current having a high frequency (the current having a fast current variation) flows through the pillar, electromagnetic waves are radiated from the pillar as a radiation noise due to the current variation.
The followings are reference documents.
[Document 1] Japanese Laid-open Patent Publication No. 2007-282324 and
[Document 2] Japanese Laid-open Patent Publication No. 2012-235639.